Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Sketchy Micro > B1. Gram positives > Flashcards

B1. Gram positives Flashcards

(59 cards)

Start Studying
1
Q

What is the gross appearance of the colonies for staph aureus?

A

Grape-like clusters

Golden yellow colonies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do you tell apart staph and strep?

A

staph are all catalase positive

catalase is enzyme that converts H2O2 to water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you tell staph aureus apart from the other staphs?

A

S. aureus is coagulase positive, all other Staphs are coagulase negative

Coagulase is enzyme that converts fibrinogen to fibrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the five characteristics on a petri-dish that you would see with staph a?

A
  1. Gram positive (violet)
  2. Catalase positive (tells you its staph)
  3. Coagulase positive (tells you its staph a)
  4. Beta-hemolytic (hemolysis of blood)
  5. Ferments mannitol (agar turns yellow)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main virulence factor for staph a?

A

Protein A

is a component of the cell wall that binds the Fc portion of antibodies, preventing opsonization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the nine diseases caused by staph a?

A 
Pneumonia
Septic arthritis
Skin infections - abscesses
Acute bacterial endocarditis
Osteomyelitis
Scalded-skin syndrome
Toxin shock syndrome
Staph food poisoning
MRSA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the appearance on x-ray film of a staph aureus infections?

A

patchy infiltrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the most common cause of septic arthritis?

A

Staph aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where does staph aureus like to colonize?

A

nares

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the most common cause of osteomyelitis in adults?

A

staph aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the toxin-mediated diseases caused by staph aureus?

A

Scalded-skin syndrome (expholiative toxin)
Toxin shock syndrome (leaving in a foreign body too long, TSS is a superantigen causing overactivation and cytokine storm)
Food poisoning - pre-formed toxin causes acute vomitting due to meats and mayo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is altered in MRSA?

A

penicillin binding proteins that are part of cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you tx MRSA?

Methicillin-sensitive staph?

A

MRSA: Vancomycin

Methicillin-sensitive is treated by nafcilin (Naf for Staf)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the most common cause of endocarditis of artificial heart valves?

A

Staph epidermis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do you treat a staph epidermidis ifx?

A

vancomycin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What organism is usually linked to infections that arise from prosthetic joints, indwelling catheters

A

staph epidermidis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why doe staph epidermidis cause blood culture contamination so much?

A

Because it’s part of the normal skin flora, so it’s easy for it to contaminate samples (e.g. drawing blood through needle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do you tell the difference between staph aureus and staph epidermidis/saprophyticus

A

Staph aureus is coagulase positive

Staph epidermidis/saprophyticus is coagulase negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do you tell the difference between staph epidermidis and saprophyticus

A

Novobiocin sensitivity

Novobiocin sensitive = S. epidermidis
Novobiocin resistant = S. saprophyticus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which staph bacteria produces biofilms?

A

S. epidermidis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a common cause of UTIs in sexually active female?

A

S. saprophyticus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Relate the following characteristics for staph saprophyticus: coagulase, catalse, urease

A

Catalse + (so it’s staph)
Coagulase - (so it’s not staph a)
Urease + (so it’s s. saprophyticus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does urease do?

A

converts urea to ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does coagulase do?

Study These Flashcards
A

Coagulase converts fibrinogen to fibrin

25
What does catalase do?
Converts H2O2 to water
26
What does beta-hemolytic mean?
Complete hemolysis of rbc
27
Fermenting mannitol turns the agar what color?
Yellow
28
What bacteria is considered to be Group A Strep?
Strep pyogenes
29
Which strep is encapsulated and contains hyaluronic acid? is it immunogenic?
Group A strep pyogenes | No, not immunogenic
30
What three skin infections does Group A strep cause?
Impetigo (honey crusted) Pharyngitis (strep throat) Erysipela and cellulitis
31
What is the most common cause of erysepilas
S. pyogenes
32
What are the three toxin-mediated diseases of Strep pyogenes?
Scarlet fever, toxic shock-like syndrome, necrotizing fasciitis
33
What are the three characteristics of scarlet fever
1. Strawberry tongue 2. Pharyngitis 3. Wide-spread rash sparring the face
34
What is necrotizing fasciitis? What causes it?
Necrotizing invades fascia underlying skin and spreads rapidly Caused by GAS (SPE-B)
35
What are SPE-A, SPE-B, SPE-C? What do they cause?
SPE = strep pyrogenic exotoxin A, C cause Toxic shock-like syndrome B causes necrotizing fasciitis
36
M Protein, which bac? What does it do? What does it lead to?
Found in GAS (pyrogenes) Main virulence factor Interferes with opsonization = antiphagocytic Induces strong humoral response = autoantibody production against cardiac myosin, leading to damaged heart valves THIS IS RHEUMATIC FEVER
37
What valve is most likely damaged with a staph aureus infection?
Tricuspid valve (due to right-sided endocarditis)
38
What valve is most likely damaged with a strep pyogenes GAS infection?
Mitral valve
39
What are the symptoms of rheumatic fever?
J - polyarthritis O - heart problems (valve damage --> murmurs, myocarditis, pericarditis) N - subcutaneous Nodules E - erythema marginatum S - Sydenham's chorea (rapid involuntary movements of hands and face)
40
What is Sydenham's chorea? What infection and condition do you see it with?
Rapid involuntary movements of hands and face GAS Rheumatic fever
41
What bacterial infection do you see PSGN in?
GAS (pyogenes)
42
How long after a GAS infection do you see PSGN?
2 weeks
43
What are some clinical features of PGSN?
Dark brown or cola colored urine | facial swelling and puffiness (edema)
44
What are the two ways to tell RF and PSGN apart?
1. RF occurs after pharyngitis, PSGN occurs after pharyngitis or skin infection 2. Early dx and tx of strep throat can prevent RF but not PSGN
45
How do you treat GAS?
Penicillin
46
What are the three main virulence factors for GAS?
1. Stretolysin O 2. Stretokinase 3. DNase
47
What does Stretolysin O do? CLinical significance?
Allows bac to lyse RBC and do beta-hemolysis | AB generated against SO. ASO titers reveal strep infection occurred recently
48
What does stretokinase do? Clinical significance?
Converts plasminogen --> plasmin (which is fibrinolytic) Given as medication to bust clots. Used in MIs, strokes, etc
49
How do you tell apart GAS and GBS in terms of antibiotics?
GAS (pyrogenes) is bacitracin SENSITIVE GBS is bacitracin RESISTANT
50
What is the enzyme that cross links the dissachs in the CW to make the peptidoglycan layer? What inactivates this enzyme? Another name for this enzyme?
Tanspeptidase located in the inner cytoplasmic membrane Penicillin binds to and inhibits it. For this reason the enzyme is also called penicillin binding protein
51
What is the importance of teichoic acid?
Polysacch present in gram (+) bacteria Important for identification of bacteria
52
Group B strep is what organism?
S. agalactiae
53
The hippurate test tells you what? | Which organism is positive for the hippurate test?
(+) Hippurate test shows that organism can hydrolyze hippurate GBS (S. agalactiae)
54
What is the CAMP test? Which organism is positive for CAMP test?
CAMP test is when you plate organism with S. aureus. (+) CAMP means that the zone of hydrolysis increased w/ S. aureus presence GBS (agalactiae)
55
What sets S. agalactiae apart from GAS?
Bacitracin resistant
56
How do you tell if S. agalactiae is different than strep pneumo and viridans?
S. agalactiae is beta hemolytic
57
What is the no. 1 cause of meningitis in neonates?
S. agalactiae
58
S. agalactiae causes which diseases? (3)
1. meningitis in neonates 2. sepsis 3. pneumonia
59
How does a neonate contact GBS? What is done to prevent this?
During delivery, if mother has GBS in vaginal canal, baby will get GBS infection Penicillin is given prophylactically

Sketchy Micro (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions